How long should I wait between vaccine doses?

Last reviewed: 2026-06-08

Quick answer

The interval depends on the vaccine; each has its own recommended number of doses and spacing. The HPV vaccine, for example, gives two doses about 6 months apart; hepatitis B is a three-dose course at 0, 1 and 6 months; a COVID-19 booster is generally given at least 6 months after the last dose or infection. Following the recommended intervals gives the best protection, and health professionals work from your vaccination record.

There's no single answer to "how long between doses", because each vaccine has its own arrangement.

The interval depends on the vaccine

Every vaccine that needs more than one dose has a spacing set by research, so the immune system produces the strongest, longest-lasting response. Common examples:

HPV vaccine: adolescents usually get two doses about 6 months apart. Older people or those with weaker immunity may need three.
Hepatitis B vaccine: the standard course is three doses at 0, 1 and 6 months.
COVID-19 booster: priority groups can generally have a booster at least 6 months after the last dose or last infection, whichever is later.

Earlier or later than scheduled

Getting the next dose too early can reduce how well the immune response works. If you're late, in most cases you don't start over; you continue from your record (see "What should I do if I miss a dose").

Health professionals set it from your record

The exact number of doses and intervals are set by health professionals based on the vaccine, your age and health, and your past vaccination record. Bringing your record to the appointment helps.

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